Medical instrument having hydrophilic member and hydrophobic member stacked

ABSTRACT

A medical instrument is disclosed having a structure capable of preventing liquid circulation between an inner layer side and an outer layer side of a peripheral wall portion. The medical instrument includes a main body portion in which a center hole and a radially outward space are partitioned by a tubular peripheral wall portion. The peripheral wall portion includes at least a first layer on which a hydrophilic member, in which a hydrophilic coating is formed on a first base portion, is disposed and a second layer on which a hydrophobic member, in which a hydrophobic coating is formed on a second base portion, is disposed. The peripheral wall portion is configured by the first layer and the second layer being stacked along a radial direction. As a result of swelling of the hydrophilic coating, the adjacent hydrophilic members come into contact with each other.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/JP2018/012137 filed on Mar. 26, 2018, which claims priority toJapanese Application No. 2017-068897 filed on Mar. 30, 2017, the entirecontent of both of which is incorporated herein by reference.

FIELD OF THE DISCLOSURE

The present disclosure relates to a medical instrument having ahydrophilic member and a hydrophobic member stacked.

BACKGROUND DISCUSSION

Hydrophilic and hydrophobic coatings are used in the field of medicalinstruments.

For example, the guide wire that is described in JP-A-2015-62512 formsan air gap between hydrophilic and hydrophobic coating films and keepsmoisture in the air gap. As a result, the guide wire exhibits lubricityeven in a situation in which the amount of the surrounding water isrelatively small.

Hydrophilic and hydrophobic polymer wires are spirally wound on thesurface of the main body of the guide wire described inJP-A-2015-181723. As a result, the guide wire exhibits slidability inboth dry and wet environments.

In each of the guide wires that are described in JP-A-2008-12276,JP-A-2008-11938, and JP-A-2007-82943, the coil portion at the distal endof the wire has an airtight structure. The coating film that covers thecoil portion is formed by lamination of a hydrophobically coated firstlayer and a hydrophilically coated second layer. As a result, the coilportion of the guide wire receives buoyancy and drooping of the distalportion attributable to gravity can be prevented.

SUMMARY

In the medical field, existing hydrophilic and hydrophobic coatings areused simply for helping ensure lubricity or forming a coating film.

In accordance with an exemplary embodiment, liquid circulation betweenthe inner and outer layer sides of a tubular peripheral wall portion canbe prevented by constituting the peripheral wall portion by means oflamination of a layer on which a hydrophilic member is disposed and alayer on which a hydrophobic member is disposed, which can be made tomedical instrument diameter reduction and performance improvement oncethe configuration is applied to a medical instrument.

In accordance with an exemplary embodiment, a medical instrument isdisclosed having a novel structure capable of preventing liquidcirculation between an inner layer side and an outer layer side of aperipheral wall portion.

In accordance with an exemplary embodiment, a medical instrument isdisclosed, which includes a main body portion in which a center hole anda radially outward space are partitioned by a tubular peripheral wallportion. The peripheral wall portion includes at least a first layerhaving a hydrophilic member including a first base portion and ahydrophilic coating formed on the first base portion; and a second layerhaving a hydrophobic member including a second base portion and ahydrophobic coating formed on the second base portion. The peripheralwall portion is formed by stacking the first layer and the second layeralong a radial direction. When the hydrophilic coating is swollen, theadjacent hydrophilic members come into contact with each other so that afirst liquid in the center hole and a second liquid present in theradially outward space are prevented from circulating through theperipheral wall portion.

In accordance with an exemplary embodiment, a medical instrument isdisclosed comprising: a main body portion having a center hole and aradially outward space partitioned by a tubular peripheral wall portion;the tubular peripheral wall portion including at least: a first layerhaving a hydrophilic member including a first base portion and ahydrophilic coating formed on the first base portion; a second layerhaving a hydrophobic member including a second base portion and ahydrophobic coating formed on the second base portion; the first layerand the second layer being stacked along a radial direction; and whereinwhen the hydrophilic coating is swollen, adjacent hydrophilic memberscome into contact with each other so that a first liquid in the centerhole and a second liquid present in the radially outward space areprevented from circulating through the tubular peripheral wall portion.

In accordance with another exemplary embodiment, a medical instrumentcomprising: an elongated tubular peripheral wall portion having acentral lumen, the tubular peripheral wall portion including at least: afirst braided layer having a hydrophilic member including a first baseportion and a hydrophilic coating formed on the first base portion; anda second braided layer having a hydrophobic member including a secondbase portion and a hydrophobic coating formed on the second baseportion, and wherein the first braided layer and the second braidedlayer are stacked along a radial direction.

In accordance with a further exemplary embodiment, a medical instrumentis disclosed comprising: a main body portion having a lumen and aradially outward space partitioned by a tubular peripheral wall portion;the tubular peripheral wall portion including at least: a first layerhaving a hydrophilic member including a first base portion and ahydrophilic coating formed on the first base portion; a second layerhaving a hydrophobic member including a second base portion and ahydrophobic coating formed on the second base portion; the first layerand the second layer being stacked along a radial direction, and whereinone of the first layer and the second layer is coiled shape, and anotherof the first layer and the second layer is mesh shaped; and wherein whenthe hydrophilic coating is swollen, adjacent hydrophilic members comeinto contact with each other so that a first liquid in the lumen and asecond liquid present in the radially outward space are prevented fromcirculating through the tubular peripheral wall portion.

In the medical instrument configured as described above, when thehydrophilic coating is swollen, the adjacent hydrophilic members comeinto contact with each other so that the first liquid in the center holeand the second liquid present in the radially outward space can beprevented from circulating through the peripheral wall portion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view illustrating the basic structure of amedical instrument having a tubular main body portion.

FIG. 1B is a cross-sectional view of a main part illustrating a statewhere a hydrophilic coating is yet to swell.

FIG. 1C is a cross-sectional view of a main part illustrating a statewhere adjacent hydrophilic members are in contact with each other as aresult of swelling of the hydrophilic coating.

FIG. 1D is a cross-sectional view of a main part illustrating a statewhere the main body portion is expanded with the hydrophilic coatingswollen.

FIG. 2A is a cross-sectional view of a main part illustrating a mainbody portion in which hydrophilic and hydrophobic members have a coilshape.

FIG. 2B is a side view illustrating a main body portion in whichhydrophilic and hydrophobic members have a mesh shape.

FIG. 2C is a longitudinal cross-sectional view illustrating the meshshape illustrated in FIG. 2B.

FIG. 2D is a cross-sectional view taken along line IID-IID of FIG. 2B.

FIG. 2E is a cross-sectional view of a main part illustrating a mainbody portion in which a mesh-shaped hydrophilic member and a coil-shapedhydrophobic member are stacked.

FIG. 2F is a cross-sectional view of a main part illustrating a mainbody portion in which a coil-shaped hydrophilic member and a mesh-shapedhydrophobic member are stacked.

FIG. 3A is a cross-sectional view schematically illustrating a main bodyportion in which a hydrophilic member, a hydrophobic member, and ahydrophilic member are sequentially stacked from an inner layer sidetoward an outer layer side.

FIG. 3B is a cross-sectional view schematically illustrating a main bodyportion in which a hydrophilic member, a hydrophobic member, and ahydrophobic member are sequentially stacked from the inner layer sidetoward the outer layer side.

FIG. 3C is a cross-sectional view schematically illustrating a main bodyportion in which a hydrophobic member, a hydrophilic member, and ahydrophobic member are sequentially stacked from the inner layer sidetoward the outer layer side.

FIG. 3D is a cross-sectional view schematically illustrating a main bodyportion in which a hydrophobic member, a hydrophilic member, and ahydrophilic member are sequentially stacked from the inner layer sidetoward the outer layer side.

FIG. 4A is a perspective view illustrating a sample corresponding to themain body portion of the medical instrument.

FIG. 4B is a lateral cross-sectional view illustrating the sample inwhich the inner layer of a peripheral wall portion is a hydrophilicfirst layer and the outer layer of the peripheral wall portion is ahydrophobic second layer.

FIG. 4C is a lateral cross-sectional view illustrating a state where aliquid leakage test is performed on the peripheral wall portion by meansof the sample illustrated in FIG. 4B.

FIG. 4D is a lateral cross-sectional view illustrating the sample inwhich the inner layer of the peripheral wall portion is the hydrophobicsecond layer and the outer layer of the peripheral wall portion is thehydrophilic first layer.

FIG. 4E is a lateral cross-sectional view illustrating a state where aliquid leakage test is performed on the peripheral wall portion by meansof the sample illustrated in FIG. 4D.

FIG. 4F is a cross-sectional view illustrating a main part of anexperimental device that conducted a test as to whether the peripheralwall portion prevents circulation of a first liquid and a second liquid.

FIG. 5 is a diagram illustrating an example in which the main bodyportion is applied to a shaft portion of a catheter.

FIG. 6 is a diagram illustrating an example in which the main bodyportion is applied to a sheath tube of a sheath.

FIG. 7A is a diagram illustrating a balloon catheter placing a stent ata desired position in a body lumen with the main body portion applied tothe stent.

FIG. 7B is an enlarged view of the distal portion of the ballooncatheter.

FIG. 7C is a plan view illustrating the pre-expanded and post-expandedshapes of the stent.

FIG. 8A is a diagram illustrating a self-expandable stent deliverysystem for placing a flow diverter stent at a desired position in thebody lumen, in which the main body portion is used to form the flowdiverter stent.

FIG. 8B is a plan view illustrating the pre-self-expanded andpost-self-expanded shapes of the flow diverter stent.

FIG. 8C is a diagram schematically illustrating a state of blood flowbetween an aneurysm and a parent blood vessel.

FIG. 8D is a diagram schematically illustrating a state where the flowdiverter stent is placed for blocking of the blood flow between theaneurysm and the parent blood vessel.

FIG. 9 is a diagram schematically illustrating a state where an embolicmaterial to which the main body portion is applied is placed in theaneurysm so that an inlet port from the parent blood vessel to theaneurysm is blocked.

FIG. 10A is an enlarged cross-sectional view illustrating the distalportion of a drug-coated balloon to which a cover member to which themain body portion is applied is attached.

FIG. 10B is a cross-sectional view illustrating a state where the covermember is increased in diameter by a balloon being inflated.

FIG. 10C is a plan view illustrating the pre-expanded and post-expandedshapes of the cover member.

DETAILED DESCRIPTION

Hereinafter, an embodiment of the disclosure will be described withreference to accompanying drawings. The following description does notlimit the technical scope or the meaning of terms described in theclaims. In the drawings, dimensional ratios are exaggerated forconvenience of description. The dimensional ratios may differ fromactual ratios.

FIG. 1A is a perspective view illustrating the basic structure of amedical instrument 10 having a tubular main body portion 20, FIG. 1B isa cross-sectional view of a main part illustrating a state where ahydrophilic coating 32 is yet to swell, and FIG. 1C is a cross-sectionalview of a main part illustrating a state where adjacent hydrophilicmembers 33 are in contact with each other as a result of swelling of thehydrophilic coating 32. FIG. 1D is a cross-sectional view of a main partillustrating a state where the main body portion 20 is expanded with thehydrophilic coating 32 swollen.

The basic structure of the medical instrument 10 will be outlined withreference to FIGS. 1A to 1D. In accordance with an exemplary embodiment,the medical instrument 10 has the main body portion 20, in which acenter hole 22 and a radially outward space 23 are partitioned by atubular peripheral wall portion 21. The peripheral wall portion 21includes at least a first layer 30 on which the hydrophilic member 33,in which the hydrophilic coating 32 is formed on a first base portion31, is disposed and a second layer 40 on which a hydrophobic member 43,in which a hydrophobic coating 42 is formed on a second base portion 41,is disposed. The peripheral wall portion 21 is formed by stacking thefirst layer 30 and the second layer 40 along a radial direction. As aresult of swelling of the hydrophilic coating 32, the adjacenthydrophilic members 33 come into contact with each other and a firstliquid 51 in the center hole 22 and a second liquid 52 present in theradially outward space 23 can be prevented from circulating through theperipheral wall portion 21 (see FIG. 1C). Once the space between theadjacent hydrophilic members 33 and the space between the adjacenthydrophobic members 43 are expanded, the first liquid 51 and the secondliquid 52 circulate through the peripheral wall portion 21 (see FIG.1D). Hereinafter, the configuration of the medical instrument 10 will bedescribed in detail.

The medical instrument 10 is used after placement into a body lumen 70(see FIGS. 1B to 1D). The first liquid 51 present in the center hole 22of the main body portion 20 and the second liquid 52 present in theradially outward space 23 of the main body portion 20 are notparticularly limited. The first liquid 51 and the second liquid 52 maybe of the same type or different types. For example, the first liquid 51is a drug solution flowing in the center hole 22 and the second liquid52 is a body fluid such as blood. In the present specification, thefirst liquid 51 includes a drug solution in which a solid drug fixed onthe inner layer side of the peripheral wall portion 21 is dissolved.Likewise, the second liquid 52 includes a drug solution in which a soliddrug fixed on the outer layer side of the peripheral wall portion 21 isdissolved.

As illustrated in FIG. 1A, the peripheral wall portion 21 has atwo-layered structure divided into the first layer 30 and the secondlayer 40. In the illustrated example, the first layer 30 constitutes theinner layer and the second layer 40 constitutes the outer layer. Thehydrophilic member 33 is disposed on the first layer 30 with thehydrophilic coating 32 applied to the first base portion 31. Thehydrophobic member 43 is disposed on the second layer 40 with thehydrophobic coating 42 applied to the second base portion 41. Asillustrated in FIGS. 1B and 1C, the first base portion 31 and the secondbase portion 41 have a wire shape (i.e., a cylindrical shape). Inaccordance with an exemplary embodiment, the hydrophilic member 33 andthe hydrophobic member 43 have a coil shape.

The preferred value of the axial length of the main body portion 20varies depending on applications and cases such as the position andthickness of the body lumen 70 to be applied. Preferably, the main bodyportion 20 has an axial length of, for example, 1 mm to 2,000 mm. Morespecifically, for example, the axial length of the main body portion 20is 1 mm to 400 mm in the case of application to a stent. The axiallength of the main body portion 20 is 300 mm to 2,000 mm in the case ofapplication to a catheter. The preferred value of the outer diameter(thickness) of the main body portion 20 varies depending on cases suchas thickness and the position of the body lumen 70 to be applied.Preferably, the main body portion 20 has an outer diameter of, forexample, 0.5 mm to 50 mm.

The first base portion 31 and the second base portion 41 materials caninclude, for example, a metal such as stainless steel (SUS), springsteel, titanium, tungsten, tantalum, and a super-elastic alloy such as anickel-titanium alloy, hard plastic such as polyimide, polyamide,polyester, polycarbonate, and a glass fiber, and a composite of thematerials. The materials of the first base portion 31 and the secondbase portion 41 may be the same as each other or different from eachother.

The shape of the first base portion 31 and the second base portion 41 isnot particularly limited. In accordance with an exemplary embodiment,the first base portion 31 and the second base portion 41 can have, forexample, a plate shape in addition to the wire shape illustrated inFIGS. 1B and 1C.

In the case of the wire shape, the preferred values of the diameters ofthe first base portion 31 and the second base portion 41 vary dependingon cases such as thickness and the position of the body lumen 70 to beapplied and the first base portion 31 and the second base portion 41preferably have an outer diameter of, for example, 0.01 mm to 0.1 mm.The diameters of the first base portion 31 and the second base portion41 may or may not be equal to each other.

In the case of the first base portion 31 and the second base portion 41having a plate shape, it is preferable that the first base portion 31and the second base portion 41 have a thickness×width of, for example,(0.01 to 0.04) mm×(0.02 to 0.2) mm. The thickness×width of the firstbase portion 31 and the thickness×width of the second base portion 41may or may not be equal to each other. In the case of the plate shape,the first base portion 31 or the second base portion 41 can be formedthinner than in the case of the wire shape. The peripheral wall portion21, which has liquid leakage prevention properties, prevents liquidcirculation between the inner layer side and the outer layer side. Inaccordance with an exemplary embodiment, an “aspect ratio of 1:1 ormore” is preferable for improvement of the liquid leakage preventionproperties. The aspect ratio is the thickness-to-width ratio of theplate.

The hydrophilic coating 32 material may be any material insofar as thematerial absorbs water and exhibits swelling properties. The material ofthe hydrophilic coating 32 can be, for example, a hydrophilic material.Examples of the hydrophilic material include known hydrophilicsubstances formed of, for example, a cellulose-based polymer substance(such as hydroxypropyl cellulose), a polyethylene oxide-based polymersubstance (such as polyethylene glycol), a maleic anhydride-basedpolymer substance (for example, a maleic anhydride copolymer such as amethyl vinyl ether-maleic anhydride copolymer), an acrylamide-basedpolymer substance (such as a block copolymer of polyglycidylmethacrylate-dimethyl acrylamide (PGMA-DMAA) and polyacrylamide),water-soluble nylon (registered trademark), polyvinyl alcohol, andpolyvinyl pyrrolidone.

The thickness of the hydrophilic coating 32 is not particularly limited.For example, it can be preferable that the hydrophilic coating 32 has athickness of 0.1 μm to 10 μm in a dry environment (DRY) and has athickness of 0.5 μm to 50 μm in a wet environment (WET). Morespecifically, for example, the thickness of the hydrophilic coating 32is 1 μm to 3 μm in the dry environment (DRY) and 10 μm to 20 μm in thewet environment (WET) in a case where a maleic anhydride-based polymersubstance constitutes the hydrophilic coating 32. The thickness of thehydrophilic coating 32 can be, for example, 1 μm to 2 μm in the dryenvironment (DRY) and 3 μm to 5 μm in the wet environment (WET) in acase where an acrylamide-based polymer substance constitutes thehydrophilic coating 32.

The hydrophobic coating 42 material may be any material insofar as thematerial exhibits hydrophobicity. The hydrophobic coating 42 materialcan be, for example, a hydrophobic material. Examples of the hydrophobicmaterial include polytetrafluoroethylene (PTFE), fluorinated ethylenepropylene (FEP), reaction-curable silicone, and a substance with lowsurface free energy terminated with alkyl and perfluoroalkyl groups. Inaddition, the hydrophobic coating 42 exhibiting hydrophobicity may beconfigured by plasma irradiation by means of a fluorine-based gas orlaser micromachining.

In accordance with an exemplary embodiment, the thickness of thehydrophobic coating 42 can be, for example, 1 μm to 40 μm in a casewhere, for example, polytetrafluoroethylene (PTFE) constitutes thehydrophobic coating 42.

As illustrated in FIGS. 1B and 1C, the first base portions 31 aredisposed at a pitch p1 (i.e., distance between a center point ofadjacent first base portions 31) which allows the swollen hydrophiliccoatings 32 of the adjacent hydrophilic members 33 to be in contact witheach other, which can help prevent the first liquid 51 and the secondliquid 52 from circulating through the peripheral wall portion 21 bybringing the adjacent hydrophilic members 33 into contact with eachother. In accordance with an exemplary embodiment, the maximum gap(pitch p1) of the lattice of the first base portion 31 can be, forexample, approximately two to six times the film thickness in the dryenvironment (DRY) although the maximum gap depends on the linearitybetween the film thickness in the dry environment (DRY) and the filmthickness in the wet environment (WET). The first base portions 31 maybe disposed at the pitch p1 or less and the adjacent hydrophilic members33 may be in contact with each other in the dry environment (DRY). Inthis case, the swollen hydrophilic coatings 32 come into contact witheach other more strongly in the wet environment (WET).

As illustrated in FIGS. 1B and 1C, the first layer 30 seals the firstliquid 51 by the swollen hydrophilic coatings 32 coming into contactwith each other. However, the first liquid 51, though minute (orrelatively very small) in amount, reaches the space between the firstlayer 30 and the second layer 40 through the hydrophilic coating 32itself. Although the second layer 40 is stacked at a position in contactwith the second liquid 52, it can be said that the second layer 40 isstacked at a position in contact with the first liquid 51 as describedabove.

Accordingly, the second base portions 41 are disposed at a pitch p2(i.e., distance between a center point of adjacent second base portions41), which sets the space between the hydrophobic coatings 42 of theadjacent hydrophobic members 43 to a dimension smaller than the gapthrough which the first liquid 51 and the second liquid 52 pass, whichcan help prevent the first liquid 51 and the second liquid 52 fromcirculating through the peripheral wall portion 21.

Wettability, capillarity, liquid viscosity, and the like relate to theelements of liquid passage through a minute (or relatively small) gap.Accordingly, the upper limit dimension of the micro gap between thehydrophobic coatings 42 varies with the material constituting thehydrophobic coating 42 and the types of the first liquid 51 and thesecond liquid 52. Although no specific dimension can be specified as theupper limit dimension of the minute gap, the upper limit dimension, forexample, is approximately 0 mm to 1 mm.

In accordance with an exemplary embodiment, as illustrated in FIG. 1C,the first liquid 51 and the second liquid 52 can be prevented fromcirculating through the peripheral wall portion 21. Starting from thisstate, the space between the adjacent hydrophilic members 33 and thespace between the adjacent hydrophobic members 43 are expanded asillustrated in FIG. 1D. The space between the adjacent hydrophilicmembers 33 and the space between the adjacent hydrophobic members 43 canbe expanded by, for example, inflation of the balloon that is disposedin the center hole 22 of the main body portion 20. As a result, thefirst liquid 51 and the second liquid 52 circulate again through theperipheral wall portion 21. In this manner, the medical instrument 10 iscapable of controlling liquid circulation through the peripheral wallportion 21. Accordingly, it is possible to prevent circulation of thefirst liquid 51 and the second liquid 52 until the main body portion 20is positioned in a desired place in the body lumen 70 and it is possibleto circulate the first liquid 51 and the second liquid 52 with the mainbody portion 20 positioned in the desired place.

FIG. 2A is a cross-sectional view of a main part illustrating a mainbody portion in which hydrophilic and hydrophobic members have a coilshape. FIG. 2B is a side view illustrating a main body portion in whichhydrophilic and hydrophobic members have a mesh shape. FIG. 2C is alongitudinal cross-sectional view illustrating the mesh shapeillustrated in FIG. 2B. FIG. 2D is a cross-sectional view taken alongline IID-IID of FIG. 2B. FIG. 2E is a cross-sectional view of a mainpart illustrating a main body portion in which a mesh-shaped hydrophilicmember and a coil-shaped hydrophobic member are stacked. FIG. 2F is across-sectional view of a main part illustrating a main body portion inwhich a coil-shaped hydrophilic member and a mesh-shaped hydrophobicmember are stacked.

The gap parts illustrated in FIGS. 2B to 2F are exaggerated in size sothat grasping of the mesh shape is facilitated. As described above, thefirst base portions 31 are disposed at the pitch p1 and the second baseportions 41 are disposed at the pitch p2.

The shape of the first base portion 31 is not particularly limited. Thefirst base portion 31 has, for example, a wire shape or a plate shape.Likewise, the shape of the second base portion 41 is not particularlylimited and the second base portion 41 has, for example, a wire shape ora plate shape. The shape of the hydrophilic member 33 is notparticularly limited. The hydrophilic member 33 has, for example, a coilshape, a ring shape, or a mesh shape. Likewise, the shape of thehydrophobic member 43 is not particularly limited and the hydrophobicmember 43 has, for example, a coil shape, a ring shape, or a mesh shape.Both the hydrophilic member 33 and the hydrophobic member 43, forexample, do not have to have a coil shape. Both the hydrophilic member33 and the hydrophobic member 43, for example, do not have to have amesh shape.

More specifically, the first base portion 31 and the second base portion41 can have a wire shape as illustrated in FIG. 2A. The hydrophilicmember 33 and the hydrophobic member 43 are formed in a coil shape. Inaccordance with an exemplary embodiment, the peripheral wall portion 21is a two-layered structure. In accordance with an exemplary embodiment,the hydrophilic first layer 30 and the hydrophobic second layer 40 canbe sequentially stacked from the inner layer toward the outer layer.

As illustrated in FIG. 2D, the first base portion 31 and the second baseportion 41 have a plate shape. Reference sign T indicates the thicknessof the plate. Reference sign W indicates the width of the plate. Asillustrated in FIGS. 2B and 2C, the hydrophilic member 33 and thehydrophobic member 43 are formed in a mesh shape. In accordance with anexemplary embodiment, the mesh shape (braided structure) can be formedby braiding of a plurality of the hydrophilic members 33 and a pluralityof the hydrophobic members 43. As in FIG. 2A, the peripheral wallportion 21 is a two-layered structure and the hydrophilic first layer 30and the hydrophobic second layer 40 are sequentially stacked from theinner layer toward the outer layer. In the illustrated example, thehydrophilic members 33 are braided and become the mesh-shapedhydrophilic first layer 30. The hydrophobic members 43 are braided onthe hydrophilic first layer 30 and become the mesh-shaped hydrophobicsecond layer 40.

As illustrated in FIG. 2E, the hydrophilic member 33 is formed in a meshshape and the hydrophobic member 43 is formed in a coil shape. As inFIG. 2A, the peripheral wall portion 21 is a two-layered structure andthe hydrophilic first layer 30 and the hydrophobic second layer 40 aresequentially stacked from the inner layer toward the outer layer.

As illustrated in FIG. 2F, the hydrophilic member 33 is formed in a coilshape and the hydrophobic member 43 is formed in a mesh shape. As inFIG. 2A, the peripheral wall portion 21 is a two-layered structure andthe hydrophilic first layer 30 and the hydrophobic second layer 40 aresequentially stacked from the inner layer toward the outer layer.

Although one wire constitutes the first base portion 31 and the secondbase portion 41 in FIG. 2A, a wire bundle in which a plurality of wiresare bundled may constitute the first base portion 31 and the second baseportion 41. In accordance with an exemplary embodiment, the main bodyportion 20 may be configured by bundling of the hydrophilic members 33and the hydrophobic members 43 that are formed in a ring shape andarranged in an axial direction.

Although the peripheral wall portion 21 needs to include at least onehydrophilic first layer 30 and at least one hydrophobic second layer 40,an appropriate selection can be made as to whether the innermost layerof the peripheral wall portion 21 will be the hydrophilic first layer 30or the hydrophobic second layer 40. In a case where another member isinserted through the center hole 22, for example, it can be preferableto use the hydrophilic first layer 30 as the innermost layer in order toenhance slidability with respect to the member. The slidability of thehydrophilic first layer 30 with respect to the member is enhanced by theinside of the center hole 22 being primed and wetted with a salinesolution or the like. The hydrophilic first layer 30 may be used as theinnermost layer in a case where it is desired to swell the innermostlayer. In accordance with an exemplary embodiment, for liquidcirculation through the center hole 22, the hydrophobic second layer 40can be used as the innermost layer.

In accordance with an exemplary embodiment, an appropriate selection canbe made as to whether the outermost layer of the peripheral wall portion21 will be the hydrophilic first layer 30 or the hydrophobic secondlayer 40. In a case where the main body portion 20 of the medicalinstrument 10 is placed into the body lumen 70, for example, thehydrophobic second layer 40 is preferably used as the outermost layer sothat no deviation is likely to occur with respect to the inner surfaceof the body lumen 70. In a case where the main body portion 20 of themedical instrument 10 moves in the body lumen 70, the slidability of themedical instrument 10 with respect to the inner surface of the bodylumen 70 should be enhanced, and thus the hydrophilic first layer 30 ismore preferable than the hydrophobic second layer 40 as the outermostlayer. In accordance with an exemplary embodiment, the hydrophilic firstlayer 30 may be used as the outermost layer in a case where it isdesired to swell the outermost layer.

FIG. 3A is a cross-sectional view schematically illustrating a main bodyportion in which a hydrophilic member, a hydrophobic member, and ahydrophilic member are sequentially stacked from the inner layer sidetoward the outer layer side. FIG. 3B is a cross-sectional viewschematically illustrating a main body portion in which a hydrophilicmember, a hydrophobic member, and a hydrophobic member are sequentiallystacked from the inner layer side toward the outer layer side. FIG. 3Cis a cross-sectional view schematically illustrating a main body portionin which a hydrophobic member, a hydrophilic member, and a hydrophobicmember are sequentially stacked from the inner layer side toward theouter layer side. FIG. 3D is a cross-sectional view schematicallyillustrating a main body portion in which a hydrophobic member, ahydrophilic member, and a hydrophilic member are sequentially stackedfrom the inner layer side toward the outer layer side.

FIGS. 3A to 3D are schematic diagrams illustrating exemplary stackedstructures. The first base portion 31 and the second base portion 41 mayhave any of the wire shape and the plate shape described above. Thehydrophilic member 33 and the hydrophobic member 43 may have any of acoil shape, a ring shape, and a mesh shape.

The peripheral wall portion 21 is not limited to the two-layeredstructures illustrated in FIGS. 2A to 2F. In accordance with anexemplary embodiment, although the peripheral wall portion 21 needs toinclude at least one hydrophilic first layer 30 and at least onehydrophobic second layer 40, the hydrophilic first layer 30 or thehydrophobic second layer 40 can be further stacked for three or morelayers to be formed.

In accordance with an exemplary embodiment, the peripheral wall portion21 is a three-layered structure as illustrated in FIG. 3A and thehydrophilic first layer 30, the hydrophobic second layer 40, and thehydrophilic first layer 30 are sequentially stacked from the inner layertoward the outer layer.

As illustrated in FIG. 3B, the peripheral wall portion 21 is athree-layered structure as in FIG. 3A and the hydrophilic first layer30, the hydrophobic second layer 40, and the hydrophobic second layer 40are sequentially stacked from the inner layer toward the outer layer.

As illustrated in FIG. 3C, the peripheral wall portion 21 is athree-layered structure as in FIG. 3A and the hydrophobic second layer40, the hydrophilic first layer 30, and the hydrophobic second layer 40are sequentially stacked from the inner layer toward the outer layer.

As illustrated in FIG. 3D, the peripheral wall portion 21 is athree-layered structure as in FIG. 3A and the hydrophobic second layer40, the hydrophilic first layer 30, and the hydrophilic first layer 30are sequentially stacked from the inner layer toward the outer layer.

Test Example

FIG. 4A is a perspective view illustrating a sample 100 corresponding tothe main body portion 20 of the medical instrument 10. FIG. 4B is alateral cross-sectional view illustrating the sample 100 in which theinner layer of the peripheral wall portion 21 is the hydrophilic firstlayer 30 and the outer layer of the peripheral wall portion 21 is thehydrophobic second layer 40. FIG. 4C is a lateral cross-sectional viewillustrating a state where a liquid leakage test is performed on theperipheral wall portion 21 by means of the sample 100 illustrated inFIG. 4B. FIG. 4D is a lateral cross-sectional view illustrating thesample 100 in which the inner layer of the peripheral wall portion 21 isthe hydrophobic second layer 40 and the outer layer of the peripheralwall portion 21 is the hydrophilic first layer 30. FIG. 4E is a lateralcross-sectional view illustrating a state where a liquid leakage test isperformed on the peripheral wall portion 21 by means of the sample 100illustrated in FIG. 4D. FIG. 4F is a cross-sectional view illustrating amain part of an experimental device 110 that conducted a test as towhether the peripheral wall portion 21 prevents circulation of the firstliquid 51 and the second liquid 52.

A plurality of the samples 100 imitating the main body portion 20 wereprepared and the test was conducted as to whether the peripheral wallportion 21 helps prevent circulation of the first liquid 51 and thesecond liquid 52.

The prepared samples 100 were divided into six types.

Sample #1: Inner layer of peripheral wall portion 21

hydrophilic first layer 30

Outer layer of peripheral wall portion 21

hydrophobic second layer 40

Sample #2: Inner layer of peripheral wall portion 21

hydrophobic second layer 40

Outer layer of peripheral wall portion 21

hydrophilic first layer 30

Sample #3: Inner layer of peripheral wall portion 21

hydrophilic first layer 30

Outer layer of peripheral wall portion 21

hydrophilic first layer 30

Sample #4: Inner layer of peripheral wall portion 21

hydrophobic second layer 40

Outer layer of peripheral wall portion 21

hydrophobic second layer 40

Sample #5: Inner layer of peripheral wall portion 21

metal-hydrophilized wire

Outer layer of peripheral wall portion 21

hydrophobic second layer 40

Sample #6: Inner layer of peripheral wall portion 21

hydrophobic second layer 40

Outer layer of peripheral wall portion 21

metal-hydrophilized wire

A pipe as a core bar (diameter: 1.77 mm), a double-sided tape fordisposing and fixing a wire around the core bar, a seal tape forpreventing water leakage from an end portion, a hydrophilic coated wire,and a hydrophobic coated wire were prepared first for the sample 100 tobe created. A guide wire (diameter: 0.46 mm) cut to 10 cm to 12 cm wasused as the hydrophilic coated wire. A hydrophilic coating formed of amaleic anhydride-based polymer substance (methyl vinyl ether-maleicanhydride copolymer) was used as the hydrophilic coating 32. APTFE-coated wire (diameter: 0.35 mm) cut to 10 cm to 12 cm was used asthe hydrophobic coated wire. Regarding Samples #5 and #6, ametal-hydrophilized wire was used by irradiation of a metal wire withplasma.

Sample #1 was created by the following procedure. First, the hydrophiliccoated wire is arranged in a planar shape on a flat surface and thedouble-sided tape is affixed to both ends of the wire. The hydrophiliccoated wire held by the tape is wound around the surface of the corebar, and then the inner layer (hydrophilic first layer 30) is formed.Next, the hydrophobic coated wire is arranged in a planar shape on aflat surface and the double-sided tape is affixed to both ends of thewire. The core bar around which the inner layer is wound is put on thehydrophobic coated wire held by the tape. The hydrophobic coated wire iswound on the inner layer, and then the outer layer (hydrophobic secondlayer 40) is formed. Subsequently, the core bar was carefully pulled outand Sample #1 was completed. The part where the core bar was pulled outcorresponds to the center hole 22 of the main body portion 20. Samples#2 to #6 were created in the same manner.

In Sample #1, 15 hydrophilic coated wires form the inner layer of theperipheral wall portion 21 and 28 hydrophobic coated wires form theouter layer of the peripheral wall portion 21 as illustrated in FIGS. 4Aand 4B. In Sample #2, 19 hydrophobic coated wires form the inner layerof the peripheral wall portion 21 and 20 hydrophilic coated wires formthe outer layer of the peripheral wall portion 21 as illustrated in FIG.4D.

As illustrated in FIG. 4F, the experimental device 110 simulated a statewhere the main body portion 20 is placed in the body lumen 70 in orderto conduct the test as to whether the peripheral wall portion 21 helpsprevent circulation of the first liquid 51 and the second liquid 52.First, the sample 100 imitating the main body portion 20 is insertedthrough a transparent tube 101 imitating the body lumen 70. The spacebetween the sample 100 and one end portion 101 a of the transparent tube101 is sealed by a seal tape 102. The other end portion 101 b of thetransparent tube 101 is directed upward and water is injected into thetransparent tube 101 by means of a pipette tube. After the transparenttube 101 is filled with the water, the space between the sample 100 andthe other end portion 101 b of the transparent tube 101 is sealed by theseal tape 102. The distal end of a syringe 103 containing water stainedwith red ink is inserted into one open end of the inner layer of thesample 100. Subsequently, the stained water was injected from thesyringe 103 into the inner layer of the sample 100. As for Sample #1, achange in the color of the water in the transparent tube 101 wasobserved as illustrated in FIG. 4C. As for Sample #2, a change in thecolor of the water in the transparent tube 101 was observed asillustrated in FIG. 4E. Likewise, a change in the color of the water inthe transparent tube 101 was observed in Samples #3 to #6.

The result of the observation is as follows.

Sample #1 (inner layer: hydrophilic, outer layer: hydrophobic): color ofwater in transparent tube 101 not changed.

Sample #2 (inner layer: hydrophobic, outer layer: hydrophilic): color ofwater in transparent tube 101 not changed.

Sample #3 (inner layer: hydrophilic, outer layer: hydrophilic): color ofwater in transparent tube 101 changed.

Sample #4 (inner layer: hydrophobic, outer layer: hydrophobic): color ofwater in transparent tube 101 changed.

Sample #5 (inner layer: metal-hydrophilized, outer layer: hydrophobic):color of water in transparent tube 101 changed.

Sample #6 (inner layer: hydrophobic, outer layer: metal-hydrophilized):color of water in transparent tube 101 changed.

As in Sample #1 (inner layer: hydrophilic, outer layer: hydrophobic) andSample #2 (inner layer: hydrophobic, outer layer: hydrophilic), liquidleakage through the peripheral wall portion 21 did not occur in the caseof lamination of the hydrophilic first layer 30 and the hydrophobicsecond layer 40.

As in Sample #3 (inner layer: hydrophilic, outer layer: hydrophilic) andSample #4 (inner layer: hydrophobic, outer layer: hydrophobic), liquidleakage through the peripheral wall portion 21 occurred in the case ofnon-lamination of the hydrophilic first layer 30 and the hydrophobicsecond layer 40.

As in Sample #5 (inner layer: metal-hydrophilized, outer layer:hydrophobic) and Sample #6 (inner layer: hydrophobic, outer layer:metal-hydrophilized), liquid leakage through the peripheral wall portion21 occurred in the metal-hydrophilized wire despite lamination of thehydrophilic layer and the hydrophobic second layer 40.

From the result of the experiment, it has been found that the liquid(stained water) in the center hole 22 and the liquid (water) present inthe radially outward space 23 can be prevented from circulating throughthe peripheral wall portion 21 by the adjacent hydrophilic coated wirescoming into contact with each other as a result of swelling of thehydrophilic coating 32 in the peripheral wall portion 21, which includesthe first layer 30 having the hydrophilic coated wire including a metalwire coated with the hydrophilic coating 32; and the second layer 40having the hydrophobic coated wire including a metal wire coated withthe hydrophobic coating 42, in which the first layer 30 and the secondlayer 40 are stacked along the radial direction.

Liquid leakage occurred in Sample #3. It is conceivable that the liquid(stained water) in the center hole 22 circulated to the liquid (water)present in the radially outward space 23 through the hydrophilic coating32 itself, even in the case of lamination of the hydrophilic first layer30 in two layers, with the limit of the amount of water retention by thehydrophilic coating 32 exceeded. Accordingly, it is conceivable that itcan be necessary to provide the hydrophobic second layer 40 sealing theliquid (stained water) in the center hole 22 as in Samples #1 and #2.

Liquid leakage occurred in Sample #4. A shortage (or lack) ofsealability is conceivable as the contact between the hydrophilic coatedwires that results from swelling of the hydrophilic coating 32 does notoccur even with the hydrophobic second layer 40 stacked in two layers.

As described above, the medical instrument 10 has the main body portion20, in which the center hole 22 and the radially outward space 23 arepartitioned by the tubular peripheral wall portion 21. The peripheralwall portion 21 includes at least the first layer 30 on which thehydrophilic member 33, in which the hydrophilic coating 32 is formed onthe first base portion 31, is disposed and the second layer 40 on whichthe hydrophobic member 43, in which the hydrophobic coating 42 is formedon the second base portion 41, is disposed. The peripheral wall portion21 includes the first layer 30 and the second layer 40 stacked along theradial direction.

In the medical instrument 10 configured as described above, the adjacenthydrophilic members 33 come into contact with each other as a result ofswelling of the hydrophilic coating 32, so that the first liquid 51 inthe center hole 22 and the second liquid 52 present in the radiallyoutward space 23 can be prevented from circulating through theperipheral wall portion 21.

In accordance with an exemplary embodiment, the first base portions 31are disposed at the pitch p1, which allows the swollen hydrophiliccoatings 32 of the adjacent hydrophilic members 33 to be in contact witheach other.

With this configuration, it is possible to prevent the first liquid 51and the second liquid 52 from circulating through the peripheral wallportion 21 by bringing the adjacent hydrophilic members 33 into contactwith each other.

The second base portions 41 are disposed at the pitch p2, which sets thespace between the hydrophobic coatings 42 of the adjacent hydrophobicmembers 43 to a dimension smaller than the gap through which the firstliquid 51 and the second liquid 52 pass.

With this configuration, it is possible to prevent the first liquid 51and the second liquid 52 from passing between the hydrophobic coatings42 of the adjacent hydrophobic members 43.

In accordance with an exemplary embodiment, the first base portion 31and the second base portion 41 have a wire shape or a plate shape.

With this configuration, application can be performed to the medicalinstrument 10 that has a shape suitable for sites to which the main bodyportion 20 is applied, which include the body lumen 70.

In accordance with an exemplary embodiment, the hydrophilic member 33and the hydrophobic member 43 can have a coil shape, a ring shape, or amesh shape.

With this configuration, application can be performed to the medicalinstrument 10 that has a shape suitable for sites to which the main bodyportion 20 is applied, which include the body lumen 70.

Next, specific application examples regarding the main body portion 20will be described. In the following description, “proximal side” refersto the side that is positioned on the side opposite to “distal side” ina case where the side that is introduced into a living body is referredto as “distal side”. In addition, the distal portion means a part thatincludes a certain range in the axial direction from the distal end(most distal end) and the proximal portion means a part that includes acertain range in the axial direction from the proximal end (mostproximal end).

Example of Application of Main Body Portion 20 to Catheter 200

FIG. 5 is a diagram illustrating an example in which the main bodyportion 20 is applied to a shaft portion 201 of a catheter 200.

Catheters such as microcatheters and guiding catheters are used fordiagnosis and treatment in body lumens. Catheters can be used forsmall-diameter peripheral regions and intricately bent blood vessels,and thus peripheral accessibility (dimensional reduction in diameter),flexibility, and torque transmission performance are required.

In an existing catheter, a composite of a metal reinforcement body layerand a resin-coated layer constitutes a wall portion. The metalreinforcement body layer provides torque transmission performance andlumen retention properties. The resin-coated layer helps prevent liquidcirculation between the inner layer side and the outer layer side of thecatheter. Accordingly, problems arise from an increase in thicknessattributable to resin coating and a decline in torque transmissionperformance attributable to viscoelastic characteristics unique toresin.

In accordance with an exemplary embodiment, the main body portion 20described above is suitable for constituting the shaft portion 201 ofthe catheter 200.

As illustrated in FIG. 5, the catheter 200 has an elongated shaftportion 201, which has a substantially circular cross section and can beintroduced into a living body, and a catheter hub 202 connected to theproximal portion of the shaft portion 201. In accordance with anexemplary embodiment, the catheter 200 has an anti-kink protector(strain relief) 203 near the interlock portion between the shaft portion201 and the catheter hub 202. The catheter 200 may not be provided withthe anti-kink protector 203. A guide wire 204 can be inserted throughthe lumen of the shaft portion 201.

The shaft portion 201 is a flexible tubular member in which an axiallyextending lumen is formed. In accordance with an exemplary embodiment,the preferred value of the length of the shaft portion 201 variesdepending on cases such as thickness and the position of a blood vesselto be applied. The length of the shaft portion 201 can be, for example,approximately 500 mm to 2,000 mm. Preferably, the length of the shaftportion 201 can be, for example, approximately 500 mm to 1,500 mm. Thepreferred value of the outer diameter (thickness) of the shaft portion201 varies depending on cases such as thickness and the position of ablood vessel to be applied. The outer diameter of the shaft portion 201can be, for example, approximately 0.4 mm to 5.0 mm. Preferably, theouter diameter of the shaft portion 201 can be, for example,approximately 0.5 mm to 3.0 mm. The preferred value of the innerdiameter of the shaft portion 201 varies depending on cases such asthickness and the position of a blood vessel to be applied. The innerdiameter of the shaft portion 201 can be, for example, approximately 0.3mm to 4.0 mm. Preferably, the inner diameter of the shaft portion 201can be, for example, approximately 0.4 mm to 2.0 mm.

In accordance with an exemplary embodiment, the first base portion 31and the second base portion 41 of the shaft portion 201 of the catheter200 have a wire shape as illustrated in FIG. 2A. The hydrophilic member33 and the hydrophobic member 43 can be formed in a coil shape.

In accordance with an exemplary embodiment, the first base portion 31and the second base portion 41 may have a plate shape as illustrated inFIGS. 2B to 2D. The hydrophilic member 33 and the hydrophobic member 43may be formed in a mesh shape.

In accordance with an exemplary embodiment, the hydrophilic member 33that has a mesh shape and the hydrophobic member 43 that has a coilshape may be stacked in the shaft portion 201 as illustrated in FIG. 2E.The hydrophilic member 33 that has a coil shape and the hydrophobicmember 43 that has a mesh shape may be stacked in the shaft portion 201as illustrated in FIG. 2F.

As illustrated in FIGS. 2A to 2F, the peripheral wall portion 21 is astructure that has at least two layers. The hydrophilic first layer 30and the hydrophobic second layer 40 are sequentially stacked from theinner layer toward the outer layer. As for the hydrophilic first layer30, the adjacent hydrophilic members 33 come into contact with eachother as a result of swelling of the hydrophilic coating 32 caused bywater, a body fluid, a drug solution, or the like. As a result, theperipheral wall portion 21 helps prevent liquid circulation between theinner layer side and the outer layer side. The hydrophobic second layer40 blocks inflow of blood outside the catheter 200 to the inner layerside.

In accordance with an exemplary embodiment, the peripheral wall portion21 can be a three-layered structure in which the hydrophilic first layer30, the hydrophobic second layer 40, and the hydrophilic first layer 30are sequentially stacked from the inner layer toward the outer layer asillustrated in FIG. 3A. Considering an actual use of the catheter 200,the hydrophilic first layer 30 is more preferable than the hydrophobicsecond layer 40 as the outermost layer, which enhances slidability withrespect to the inner surface of the body lumen 70 in that the catheter200 is the medical instrument 10 that moves in the body lumen 70.

In accordance with an exemplary embodiment, the layered structure of thecatheter 200 may not be constant from the proximal portion to the distalportion. For example, the hydrophilic first layer 30, the hydrophobicsecond layer 40, and the hydrophilic first layer 30 may be sequentiallystacked from the inner layer toward the outer layer on the distal side(stacked structure in FIG. 3A) with the hydrophobic second layer 40, thehydrophilic first layer 30, and the hydrophobic second layer 40sequentially stacked from the inner layer toward the outer layer on theproximal side (stacked structure in FIG. 3C).

In accordance with an exemplary embodiment, a resin-coated layer (i.e.,an inner layer plus (+) an outer layer) and a reinforcement body layerform a stacked structure constituting a catheter wall portion of anexisting catheter. The resin-coated layer is to prevent liquidcirculation between inside and outside layers of a shaft portion. Thereinforcement body layer is formed by coil winding of a metal wire(φ0.04 mm (i.e., an outer diameter of 0.04 mm)) on the inner layer andcoated with the outer layer. In accordance with an exemplary embodiment,the catheter wall portion, for example, has a thickness of 0.15 mm and acatheter diameter of 0.3 mm.

The shaft portion 201 of the catheter 200 of the present embodiment hasa structure in which the hydrophilic member 33 (φ0.04 mm) and thehydrophobic member 43 (φ0.04 mm) are stacked. A resin-coated layer forpreventing liquid circulation between the inner layer side and the outerlayer side of the shaft portion 201 is unnecessary in this exemplaryembodiment, and thus the wall portion of the catheter 200 of the presentembodiment can be, for example, 0.08 mm and the catheter diameter canbe, for example, 0.16 mm. Accordingly, the catheter 200 of the presentembodiment can be, for example, 0.14 mm smaller in catheter diameterthan the existing catheter.

As described above, the main body portion 20 constitutes the shaftportion 201 of the catheter 200.

In this configuration, the shaft portion 201 of the catheter 200 iscapable of suppressing liquid circulation between the inner layer sideand the outer layer side, for example, by means of nothing but thestacked structure of the hydrophilic member 33 and the hydrophobicmember 43. In accordance with this exemplary embodiment, the catheter200 does not require any resin-coated layer for preventing liquidcirculation between the inner layer side and the outer layer side of theshaft portion 201, and thus the diameter of the catheter 200 can bereduced. As a result, the peripheral accessibility and torquetransmission performance of the catheter can be improved. Also, in thecase of a guiding catheter, a reduction in outer diameter is possible ascompared with an existing catheter of the same inner diameter, and thusa puncture portion can be reduced in size. Further, an increase in innerdiameter is possible as compared with an existing catheter of the sameouter diameter, and thus a device with a larger outer diameter can beinserted through the lumen of the shaft portion 201.

Example of Application of Main Body Portion 20 to Sheath 300

FIG. 6 is a diagram illustrating an example in which the main bodyportion 20 is applied to a sheath tube 301 of a sheath 300.

The illustrated sheath 300 is an introducer sheath 300.

A sheath percutaneously inserted into a body lumen is used so that anelongated body inserted into the body lumen is guided. It is preferablethat the sheath has a small outer diameter, which is because a puncturesite resulting from the sheath is less likely to lead to complicationswhen the site is relatively small. Considering the relationship betweenthe kink resistance of the sheath and the device dimension of insertion,the inner and outer diameters of the sheath are strictly limited.

Existing sheaths are resin-molded articles, and thus have the demerits(or limitations) of being limited in terms of thickness reduction andbeing prone to kinks.

In accordance with an exemplary embodiment, a sheath can be formed witha braided metal wire alone and without a resin-coated layer in order toachieve both kink resistance and thickness reduction. However, druginjection or the like can be performed through the sheath in some cases,and thus it is desired that no liquid circulates between the inner andouter layer sides of the sheath.

In accordance with an exemplary embodiment, the main body portion 20described above is suitable for constituting the sheath tube 301 of theintroducer sheath 300 to be percutaneously inserted into the body lumen70.

As illustrated in FIG. 6, an introducer assembly 302 has the introducersheath 300 securing an access route into a body-cavity and a dilator 303assisting with insertion of the introducer sheath 300. The introducersheath 300 is provided with the sheath tube 301, a sheath hub 304, and ahemostatic valve 305. The dilator 303 is inserted through the sheathtube 301 and the distal portion of the dilator 303 protrudes from thedistal end of the sheath tube 301. The dilator 303 has a dilator hub 306connected to the sheath hub 304.

In the sheath tube 301 of the introducer sheath 300, the first baseportion 31 and the second base portion 41 have a plate shape asillustrated in FIGS. 2B to 2D. The hydrophilic member 33 and thehydrophobic member 43 are formed in a mesh shape.

The first base portion 31 and the second base portion 41 may have a wireshape as illustrated in FIG. 2A. The hydrophilic member 33 and thehydrophobic member 43 may be formed in a coil shape.

In accordance with an exemplary embodiment, the hydrophilic member 33that has a mesh shape and the hydrophobic member 43 that has a coilshape may be stacked in the sheath tube 301 as illustrated in FIG. 2E.The hydrophilic member 33 that has a coil shape and the hydrophobicmember 43 that has a mesh shape may be stacked in the sheath tube 301 asillustrated in FIG. 2F.

As illustrated in FIGS. 2A to 2F, the peripheral wall portion 21 is astructure that has at least two layers. The hydrophilic first layer 30and the hydrophobic second layer 40 are sequentially stacked from theinner layer toward the outer layer. As for the hydrophilic first layer30, the adjacent hydrophilic members 33 come into contact with eachother as a result of swelling of the hydrophilic coating 32 caused bywater, a body fluid, a drug solution, or the like. As a result, theperipheral wall portion 21 helps prevent liquid circulation between theinner layer side and the outer layer side. The hydrophobic second layer40 blocks inflow of blood outside the introducer sheath 300 to the innerlayer side.

In accordance with an exemplary embodiment, the peripheral wall portion21 can be a three-layered structure in which the hydrophilic first layer30, the hydrophobic second layer 40, and the hydrophilic first layer 30are sequentially stacked from the inner layer toward the outer layer asillustrated in FIG. 3A. Considering an actual use of the introducersheath 300, the hydrophilic first layer 30 is more preferable than thehydrophobic second layer 40 as the outermost layer, which enhancesslidability with respect to the inner surface of the body lumen 70 inthat the introducer sheath 300 is the medical instrument 10 that movesin the body lumen 70.

In accordance with an exemplary embodiment, the layered structure of theintroducer sheath 300 may not be constant from the proximal portion tothe distal portion. For example, the hydrophilic first layer 30, thehydrophobic second layer 40, and the hydrophilic first layer 30 may besequentially stacked from the inner layer toward the outer layer on thedistal side (stacked structure in FIG. 3A) with the hydrophobic secondlayer 40, the hydrophilic first layer 30, and the hydrophobic secondlayer 40 sequentially stacked from the inner layer toward the outerlayer on the proximal side (stacked structure in FIG. 3C).

As described above, the main body portion 20 constitutes the sheath tube301 of the introducer sheath 300 to be percutaneously inserted into thebody lumen 70.

With this configuration, it is possible to provide the sheath tube 301achieving both kink resistance and thickness reduction. The sheath tube301 of the introducer sheath 300 is capable of suppressing liquidcirculation between the inner layer side and the outer layer side, forexample, by means of nothing but the stacked structure of thehydrophilic member 33 and the hydrophobic member 43. The introducersheath 300 does not require any resin-coated layer for preventing liquidcirculation between the inner layer side and the outer layer side of thesheath tube 301, and thus the relatively small-diameter andhigh-flexibility introducer sheath 300 can be obtained. As a result, theintroducer sheath 300 can be used for thin blood vessels or punctureportion size reduction. Further, an increase in the inner diameter ofthe introducer sheath 300 is possible as compared with an existingintroducer sheath of the same outer diameter, and thus a device with alarger outer diameter can be inserted through the lumen of the shaftportion 201.

Example of Application of Main Body Portion 20 to Stent 400

FIG. 7A is a diagram illustrating a balloon catheter 401 placing a stent400 at a desired position in the body lumen 70 with the main bodyportion 20 applied to the stent 400. FIG. 7B is an enlarged view of thedistal portion of the balloon catheter 401. FIG. 7C is a plan viewillustrating the pre-expanded and post-expanded shapes of the stent 400.

The gap parts illustrated in FIGS. 7A to 7C are exaggerated in size sothat grasping of the mesh shape of the stent 400 is facilitated. Asdescribed above, the first base portions 31 are disposed at the pitch p1and the second base portions 41 are disposed at the pitch p2.

Stent placement for placing a stent is performed as a method fortreating a lesion area (stenosed site) formed in a blood vessel or thelike. In general, a balloon catheter is used as a delivery device duringstent placement into a lesion area.

In a non-expanded state, the stent is held (mounted) on the outersurface of a balloon folded on the outer periphery of a shaft. Once thestent is delivered to the lesion area, the stent is expanded by theballoon and placed into the lesion area in an expanded state. As aresult of the stent placement into the lesion area, the lesion area iswidened by the expansion force of the stent. Examples of the stentinclude a balloon expandable stent for use in coronary arteries and aballoon expandable stent for use in peripheral blood vessels.

In the case of an existing stent, liquid circulation occurs between theinner and outer layers of the stent after the stent is placed into abody lumen. Accordingly, the drug that is applied to the outermost layerof the stent flows out to the inner layer side of the stent withouttransition to a target lesion area. In addition, the drug that isapplied to the innermost layer of the stent flows out to the outer layerside of the stent without transition to the target lesion area. As aresult, problems can arise from a decline in the effects of the drugs onthe outermost and innermost layers.

The main body portion 20 described above is suitable for constitutingthe stent 400 placed into the body lumen 70.

In the balloon catheter 401 for stent delivery, the stent 400 is mountedon a balloon 402 that is in a deflated state as illustrated in FIG. 7A.The balloon catheter 401 has an elongated shaft 403, the inflatable anddeflatable balloon 402 provided on the distal side of the shaft 403, anda hub 404 fixed to the proximal end of the shaft 403.

As illustrated in FIG. 7B, the shaft 403 has an outer tube 405 and aninner tube 406 inserted through the lumen of the outer tube 405. Ahollow tube shaped body constitutes the outer tube 405. An inflationlumen through which an inflation fluid for inflating the balloon 402circulates is formed between the outer tube 405 and the inner tube 406.A guide wire lumen is formed in the inner tube 406. A guide wire 407,which guides the balloon 402 to a lesion area, is inserted through theguide wire lumen.

As illustrated in FIG. 7A, the balloon catheter 401 is configured as aso-called rapid exchange-type catheter in which the guide wire 407 isintroduced into the inner tube 406 via an opening portion 408 for aguide wire, which is formed between the distal side and the proximalside of the shaft 403. Alternatively, the balloon catheter 401 may beconfigured as a so-called over-the-wire catheter.

The distal portion of the inner tube 406 penetrates the inner portion ofthe balloon 402 and is open on the distal side that is beyond theballoon 402 as illustrated in FIG. 7B. In accordance with an exemplaryembodiment, the inner tube 406 can be provided with contrast markers 409a and 409 b.

The proximal portion of the balloon 402 is fixed to the distal portionof the outer tube 405 and the distal portion of the balloon 402 is fixedto the distal portion of the inner tube 406. In the deflated state, theballoon 402 is folded so as to be wound around the outer periphery ofthe inner tube 406.

In accordance with an exemplary embodiment, the first base portion 31and the second base portion 41 of the stent 400 have a plate shape asillustrated in FIGS. 2B to 2D. The hydrophilic member 33 and thehydrophobic member 43 are formed in a mesh shape and constitute a stentstrut.

As illustrated in FIG. 3B, the peripheral wall portion 21 has athree-layered structure. The hydrophilic first layer 30, the hydrophobicsecond layer 40, and the hydrophobic second layer 40 are sequentiallystacked from the inner layer toward the outer layer. The hydrophobicsecond layer 40, the hydrophilic first layer 30, and the hydrophobicsecond layer 40 may be sequentially stacked from the inner layer towardthe outer layer, as illustrated in FIG. 3C, in the peripheral wallportion 21. As for the hydrophilic first layer 30, the adjacenthydrophilic members 33 come into contact with each other as a result ofswelling of the hydrophilic coating 32 caused by blood. As a result, theperipheral wall portion 21 helps prevent liquid circulation between theinner layer side and the outer layer side. Considering an actual use ofthe stent 400, the hydrophobic second layer 40 is more preferable thanthe hydrophilic first layer 30 as the outermost layer to reduce thepossibility of deviation with respect to the inner surface of the bodylumen 70 in that the stent 400 needs to be pressure-joined to a bloodvessel wall.

In accordance with an exemplary embodiment, the innermost layer of thestent 400 is coated with a drug (antiplatelet drug) preventing thrombusformation and biodegradable plastic. The drug can be released slowly bygradual degradation of the biodegradable plastic.

In general, an antiplatelet drug is taken, for example, for three monthto 12 months or more, for stent thrombosis prevention in a case wherethe stent 400 is placed in a blood vessel. Since the stent 400 hassustained drug-release properties, the stent 400 eliminates the need forpatients' medication and is capable of making a contribution bypreventing a patient from forgetting to take his or her medicine andimproving the patient's quality of life (QOL).

In accordance with an exemplary embodiment, the first base portion 31and the second base portion 41 constituting the stent 400 may have awire shape as illustrated in FIG. 2A. The hydrophilic member 33 and thehydrophobic member 43 may be formed in a coil shape.

As illustrated in FIG. 7C, the stent 400 changes from the pre-expandedshape illustrated on the upper side to the post-expanded shapeillustrated on the lower side. Once the balloon 402 is inflated and thestent 400 is increased in diameter as a result, the longitudinal lengthof the stent 400 (length in the left-right direction in the drawing)decreases. It is possible to reduce the gap of the stent strut byincreasing the mesh angle that is indicated by reference sign θ in thedrawing. In a case where the hydrophilic member 33 and the hydrophobicmember 43 are formed in a coil shape, the gap of the stent strut can bereduced by an increase in coil angle.

The stent 400 is placed at a target site in the body lumen 70 by theballoon catheter 401. The gap of the stent strut decreases after thestent 400 is expanded. Further, the adjacent hydrophilic members 33 comeinto contact with each other as a result of swelling of the hydrophiliccoating 32 caused by blood. As a result, the stent 400 blocks blood flowfrom the inner layer side to the outer layer side. Meanwhile, blood flowcan be ensured in the stent 400.

As described above, the main body portion 20 constitutes the stent 400placed into the body lumen 70.

In this configuration, the stent 400 placed into the body lumen 70 iscapable of suppressing liquid circulation between the inner layer sideand the outer layer side, for example, by means of nothing but thestacked structure of the hydrophilic member 33 and the hydrophobicmember 43. As for the expandable stent 400 ensuring blood flow, a drugpreventing neointima growth can be applied to the outermost layer of thestent 400 and a drug preventing thrombus formation can be applied to theinnermost layer of the stent 400. As a result of the liquid circulationprevention between the inner and outer layers of the stent 400,transition to a target lesion area can be achieved for each of the drugson the outermost and innermost layers. Accordingly, the drugs areefficacious in a suitable manner based on the absence of liquidcirculation and performance improvement is achieved in terms ofneointima growth prevention and thrombus formation prevention.

Example of Application of Main Body Portion 20 to Flow Diverter Stent450

FIG. 8A is a diagram illustrating a self-expandable stent deliverysystem 451 for placing a flow diverter stent 450 at a desired positionin the body lumen 70 in which the main body portion 20 is used to formthe flow diverter stent 450. FIG. 8B is a plan view illustrating thepre-self-expanded and post-self-expanded shapes of the flow diverterstent 450. FIG. 8C is a diagram schematically illustrating a state ofblood flow between an aneurysm 421 and a parent blood vessel 422. FIG.8D is a diagram schematically illustrating a state where the flowdiverter stent 450 is placed for blocking of the blood flow between theaneurysm 421 and the parent blood vessel 422.

The gap parts illustrated in FIG. 8B are exaggerated in size so thatgrasping of the mesh shape of the flow diverter stent 450 isfacilitated. As described above, the first base portions 31 are disposedat the pitch p1 and the second base portions 41 are disposed at thepitch p2.

In recent years, flow diverter placement as well as coil-basedembolization has attracted attention as a cerebrovascular aneurysmtreatment method. The flow diverter placement is a treatment method forcausing aneurysm clotting and preventing rupture by means of flowdiverter stent placement between an aneurysm and a parent blood vesseland blocking of blood flow from the parent blood vessel into theaneurysm.

An existing flow diverter stent has a precise blade mesh structure inwhich blood flow between an aneurysm and a parent blood vessel isblocked by surface tension. However, blood circulation occurs to someextent between the aneurysm and the parent blood vessel, and thus arelatively long time is required for the aneurysm clotting. The aneurysmmay rupture before clotting, and thus it is necessary to block the bloodflow between the aneurysm and the parent blood vessel.

In accordance with an exemplary embodiment, the main body portion 20described above is suitable for constituting the flow diverter stent 450for blocking blood flow between the inner and outer layer sides and foruse in blocking of blood flow between the aneurysm 421 and the parentblood vessel 422.

In accordance with an exemplary embodiment, the flow diverter stent 450is a self-expandable stent. As illustrated in FIG. 8A, theself-expandable stent delivery system 451 has an inner tube 452, anouter tube 454, the flow diverter stent 450, and a hand operation unit455. The inner tube 452 is provided with a guide wire lumen 453 throughwhich a guide wire is inserted. The outer tube 454 is disposed so as tocover the distal portion side of the inner tube 452. The flow diverterstent 450 is disposed between the distal portion of the inner tube 452and the distal portion of the outer tube 454. The flow diverter stent450 is released from the space between the inner tube 452 and the outertube 454, expanded, and deformed as the outer tube 454 moves. The handoperation unit 455 is disposed on the proximal side of the inner tube452 and configured to be grippable, for example, by a user. Theself-expandable stent delivery system 451 is capable of inserting theinner tube 452 and the outer tube 454 along the guide wire into anintra-body target site. After the flow diverter stent 450 is releasedand placed into the body, the outer tube 454 and the inner tube 452 areremoved to the outside the body.

The first base portion 31 and the second base portion 41 of the flowdiverter stent 450 have a plate shape as illustrated in FIGS. 2B to 2D.The hydrophilic member 33 and the hydrophobic member 43 are formed in amesh shape and constitute a stent strut.

As illustrated in FIG. 3B, the peripheral wall portion 21 has athree-layered structure. The hydrophilic first layer 30, the hydrophobicsecond layer 40, and the hydrophobic second layer 40 are sequentiallystacked from the inner layer toward the outer layer. The hydrophobicsecond layer 40, the hydrophilic first layer 30, and the hydrophobicsecond layer 40 may be sequentially stacked from the inner layer towardthe outer layer, as illustrated in FIG. 3C, in the peripheral wallportion 21. As for the hydrophilic first layer 30, the adjacenthydrophilic members 33 come into contact with each other as a result ofswelling of the hydrophilic coating 32 caused by blood. As a result, theperipheral wall portion 21 helps prevent liquid circulation between theinner layer side and the outer layer side. Considering an actual use ofthe flow diverter stent 450, the hydrophobic second layer 40, forexample, is more preferable than the hydrophilic first layer 30 as theoutermost layer to reduce the possibility of deviation with respect tothe inner surface of the body lumen 70 in that the flow diverter stent450 needs to be pressure-joined to a blood vessel wall.

The innermost layer of the flow diverter stent 450 is coated with a drug(antiplatelet drug) preventing thrombus formation and biodegradableplastic. The drug can be released slowly by gradual degradation of thebiodegradable plastic.

In general, an antiplatelet drug is taken, for example, for three monthsto 12 months or more, for stent thrombosis prevention in a case wherethe flow diverter stent 450 is placed in a blood vessel. Since the flowdiverter stent 450 has sustained drug-release properties, the flowdiverter stent 450 eliminates the need for patients' medication and iscapable of making a contribution by preventing a patient from forgettingto take his or her medicine and improving the patient's quality of life(QOL).

The first base portion 31 and the second base portion 41 of the flowdiverter stent 450 may have a wire shape as illustrated in FIG. 2A. Thehydrophilic member 33 and the hydrophobic member 43 may be formed in acoil shape.

As illustrated in FIG. 8B, the flow diverter stent 450 changes from thepre-self-expanded shape illustrated on the upper side to thepost-self-expanded shape illustrated on the lower side. Once aself-increase in the diameter of the flow diverter stent 450 occurs, thelongitudinal length of the flow diverter stent 450 (length in theleft-right direction in the drawing) decreases. It is possible to reducethe gap of the stent strut by increasing the mesh angle that isindicated by reference sign θ in the drawing. In a case where thehydrophilic member 33 and the hydrophobic member 43 are formed in a coilshape, the gap of the stent strut can be reduced by an increase in coilangle. The flow diverter stent 450 helps prevent liquid circulationbetween the inner layer side and the outer layer side even afterself-expansion.

Blood flow occurs between the aneurysm 421 and the parent blood vessel422 as indicated by the solid-line arrows in FIG. 8C, and then theaneurysm 421 becomes relatively large as indicated by the white arrowsin FIG. 8C.

As illustrated in FIG. 8D, the flow diverter stent 450 is placed betweenthe aneurysm 421 and the parent blood vessel 422. The gap of the stentstrut decreases after self-expansion of the flow diverter stent 450.Further, the adjacent hydrophilic members 33 come into contact with eachother as a result of swelling of the hydrophilic coating 32 caused byblood. As a result, the flow diverter stent 450 blocks blood flow fromthe inner layer side to the outer layer side, that is, from the parentblood vessel 422 side to the aneurysm 421 side. Meanwhile, blood flow isensured in the flow diverter stent 450. By blocking the aneurysm 421from the parent blood vessel 422, it is possible to cause the aneurysm421 to clot relatively early and help prevent rupture.

As described above, the main body portion 20 constitutes the flowdiverter stent 450 blocking blood flow between the inner and outer layersides and used for blocking of blood flow between the aneurysm 421 andthe parent blood vessel 422.

In this configuration, the flow diverter stent 450 is capable ofsuppressing liquid circulation between the inner layer side and theouter layer side by means of nothing but the stacked structure of thehydrophilic member 33 and the hydrophobic member 43. The flow diverterstent 450 is capable of blocking blood flow from the parent blood vessel422 to the aneurysm 421 side and maintaining blood flow in the flowdiverter stent 450. The flow diverter stent 450 is capable of causingthe aneurysm 421 to clot relatively early and preventing rupture byblocking the aneurysm 421 from the parent blood vessel 422.

A drug preventing neointima growth can be applied to the outermost layerof the flow diverter stent 450 and a drug preventing thrombus formationcan be applied to the innermost layer of the flow diverter stent 450 asin the case of the stent 400. As a result of the liquid circulationprevention between the inner and outer layers of the flow diverter stent450, transition to a target lesion area can be achieved for each of thedrugs on the outermost and innermost layers. Accordingly, the drugs areefficacious in a suitable manner based on the absence of liquidcirculation and performance improvement is achieved in terms ofneointima growth prevention and thrombus formation prevention.

Stent graft placement is known as an aortic aneurysm treatment method.The stent graft placement is means for preventing aneurysm rupture, forexample, by means of stent-based support and placement of a graft thatreinforces a blood vessel wall from the inside. In accordance withexemplary embodiment, the graft can be an artificial blood vessel inwhich water-repellent fibers are braided.

The flow diverter stent 450 of the present embodiment can be used as astent graft since the flow diverter stent 450 helps prevent liquidcirculation between the inner layer and the outer layer. In this case,no graft as a fiber layer is necessary, and thus a small-diameter andhigh-flexibility stent graft can be obtained. As a result, the stentgraft can be used for thin blood vessels as well.

Example of Application of Main Body Portion 20 to Embolic Material 500

FIG. 9 is a diagram schematically illustrating a state where an embolicmaterial 500 to which the main body portion 20 is applied is placed inthe aneurysm 421 so that an inlet port 423 from the parent blood vessel422 to the aneurysm 421 is blocked.

As described above, coil-based embolization is known as acerebrovascular aneurysm treatment method. Even with an aneurysm filledwith coils, however, an inlet port from a parent blood vessel to theaneurysm cannot be blocked with ease due to the presence of the minutegaps between the coils. Blood circulation occurs to some extent betweenthe aneurysm and the parent blood vessel, and thus a relatively longtime can be required for aneurysm clotting. The aneurysm may rupturebefore clotting, and thus it is necessary to block the blood flowbetween the aneurysm and the parent blood vessel. The main body portion20 described above is suitable for constituting the embolic material 500blocking blood flow between the inner and outer layer sides and used forblocking the inlet port 423 from the parent blood vessel 422 to theaneurysm 421 by being placed into the aneurysm 421.

As illustrated in FIG. 9, the embolic material 500 is formed in a meshshape. The peripheral wall portion 21 has a three-layered structure asin the case of the stent 400 described above. The hydrophilic firstlayer 30, the hydrophobic second layer 40, and the hydrophobic secondlayer 40 are sequentially stacked from the inner layer toward the outerlayer (stacked structure in FIG. 3B). The hydrophobic second layer 40,the hydrophilic first layer 30, and the hydrophobic second layer 40 maybe sequentially stacked from the inner layer toward the outer layer inthe peripheral wall portion 21 (stacked structure in FIG. 3C). As forthe hydrophilic first layer 30, the adjacent hydrophilic members 33 comeinto contact with each other as a result of swelling of the hydrophiliccoating 32 caused by blood. As a result, the peripheral wall portion 21helps prevent blood circulation at the inlet port 423. Considering anactual use of the embolic material 500, the hydrophobic second layer 40is more preferable than the hydrophilic first layer 30 as the outermostlayer to reduce the possibility of deviation with respect to the innersurface of the body lumen 70 in that the embolic material 500 needs tobe pressure-joined to a blood vessel wall.

In accordance with an exemplary embodiment, the innermost layer of theembolic material 500 is coated with a drug promoting blood coagulationand biodegradable plastic. The drug can be released, for example, slowlyby gradual degradation of the biodegradable plastic.

Since the embolic material 500 has sustained drug-release properties,the embolic material 500 helps eliminate the need for patients'medication and is capable of making a contribution by preventing apatient from forgetting to take his or her medicine and improving thepatient's quality of life (QOL).

As illustrated in FIG. 9, the inlet port 423 from the parent bloodvessel 422 to the aneurysm 421 is blocked by the mesh-shaped embolicmaterial 500 being placed into the aneurysm 421. The adjacenthydrophilic members 33 come into contact with each other as a result ofswelling of the hydrophilic coating 32 caused by blood. As a result, theembolic material 500 blocks blood flow from the inlet port 423 to theaneurysm 421 side. By blocking the aneurysm 421 from the parent bloodvessel 422, it is possible to cause the aneurysm 421 to clot relativelyearly and prevent rupture.

As described above, the main body portion 20 is suitable forconstituting the embolic material 500 blocking blood flow between theinner and outer layer sides and used for blocking the inlet port 423from the parent blood vessel 422 to the aneurysm 421 by being placedinto the aneurysm 421.

In this configuration, the embolic material 500 is capable ofsuppressing liquid circulation between the inner layer side and theouter layer side, for example, by means of nothing but the stackedstructure of the hydrophilic member 33 and the hydrophobic member 43 andblocks blood flow from the inlet port 423 to the aneurysm 421 side. Theembolic material 500 is capable of causing the aneurysm 421 to clotrelatively early and preventing rupture by blocking the aneurysm 421from the parent blood vessel 422.

In accordance with an exemplary embodiment, a drug promoting bloodcoagulation can be applied to the innermost layer of the embolicmaterial 500. As a result of the liquid circulation prevention betweenthe inner and outer layers of the embolic material 500, transition to atarget lesion area is achieved for the drug on the innermost layer.Accordingly, the drug is efficacious in a suitable manner based on theabsence of liquid circulation and performance improvement is achieved interms of blood coagulation promotion.

Example of Application of Main Body Portion 20 to Cover Member 600 forDrug-Coated Balloon 601

FIG. 10A is an enlarged cross-sectional view illustrating the distalportion of a drug-coated balloon 601 to which a cover member 600 towhich the main body portion 20 is applied is attached. FIG. 10B is across-sectional view illustrating a state where the cover member 600 isincreased in diameter by a balloon 602 being inflated. FIG. 10C is aplan view illustrating the pre-expanded and post-expanded shapes of thecover member 600. Regarding the configuration of the balloon 602,members that are in common with those illustrated in FIG. 7B are denotedby the same reference signs with descriptions of the members partiallyomitted.

A drug-coated balloon (DCB) is a drug delivery system (DDS) applying adrug to a target blood vessel site with the drug applied to the surfaceof a balloon. The drug applied to the balloon flows out when thedrug-coated balloon is taken out from a holder tube or accesses thetarget site. Accordingly, at present, effective drug application orrelease is impossible at target sites.

In accordance with an exemplary embodiment, the main body portion 20described above is suitable for constituting the tubular cover member600 used so that the periphery of the balloon 602 is covered in thedrug-coated balloon 601 in which a drug 603 is applied to the surface ofthe balloon 602. The cover member 600 operates the balloon 602 with theballoon 602 positioned at a target site. As a result, the cover member600 allows the drug 603 positioned on the inner layer side of the covermember 600 to be released to the outer layer side of the cover member600.

As illustrated in FIGS. 10A to 10C, the first base portion 31 and thesecond base portion 41 of the cover member 600 have a plate shape. Thehydrophilic member 33 and the hydrophobic member 43 are formed in a meshshape.

As illustrated in FIG. 3A, the peripheral wall portion 21 has athree-layered structure. The hydrophilic first layer 30, the hydrophobicsecond layer 40, and the hydrophilic first layer 30 are sequentiallystacked from the inner layer toward the outer layer. The hydrophobicsecond layer 40, the hydrophilic first layer 30, and the hydrophilicfirst layer 30 may be sequentially stacked from the inner layer towardthe outer layer, as illustrated in FIG. 3D, in the peripheral wallportion 21. As for the hydrophilic first layer 30, the adjacenthydrophilic members 33 come into contact with each other as a result ofswelling of the hydrophilic coating 32 caused by a drug solution orwater. As a result, the peripheral wall portion 21 helps prevent liquidcirculation between the inner layer side and the outer layer side.Considering an actual use of the cover member 600, the hydrophilic firstlayer 30 is more preferable than the hydrophobic second layer 40 as theoutermost layer to enhance slidability with respect to the inner surfaceof the body lumen 70 in that the cover member 600 is the medicalinstrument 10 that moves in the body lumen 70.

The first base portion 31 and the second base portion 41 of the covermember 600 may have a wire shape as illustrated in FIG. 2A. Thehydrophilic member 33 and the hydrophobic member 43 may be formed in acoil shape.

As illustrated in FIG. 10C, the cover member 600 changes from thepre-expanded shape illustrated on the upper side to the post-expandedshape illustrated on the lower side. When the balloon 602 is inflatedand the cover member 600 is increased in diameter as a result, thelongitudinal length of the cover member 600 (length in the left-rightdirection in the drawing) decreases or both end parts become denser. Thegap can be increased in diameter and enlarged by the mesh angle that isindicated by reference sign θ in the drawing being reduced. In a casewhere the hydrophilic member 33 and the hydrophobic member 43 are formedin a coil shape, the gap can be enlarged by a reduction in coil angle.

The layer of the drug 603 is disposed between the outer peripheralsurface of the balloon 602 and the inner peripheral surface of the covermember 600.

As illustrated in FIG. 10A, the cover member 600 covers the periphery ofthe balloon 602 of the drug-coated balloon 601 in a state where theballoon 602 is closed. Since the layer of the drug 603 is covered by thecover member 600, the drug 603 is prevented from flowing out when thedrug-coated balloon 601 is taken out from a holder tube or accesses atarget site in a blood vessel.

As illustrated in FIG. 10B, the balloon 602 is operated once the balloon602 reaches the target site. Once the balloon 602 is inflated and thecover member 600 is increased in diameter as a result, the mesh angle θdecreases and the gap becomes relatively large. The space between theadjacent hydrophilic members 33 and the space between the adjacenthydrophobic members 43 are expanded. As a result, the drug 603 isreleased from the inner layer side of the cover member 600 toward theouter layer side of the cover member 600 and transition to the targetsite occurs. As a result, the drug 603 can be effectively applied orreleased at the target site.

As described above, the main body portion 20 constitutes the tubularcover member 600 used so that the periphery of the balloon 602 iscovered in the drug-coated balloon 601 in which the drug 603 is appliedto the surface of the balloon 602. The cover member 600 operates theballoon 602 with the balloon 602 positioned at a target site. As aresult, the cover member 600 allows the drug 603 positioned on the innerlayer side to be released to the outer layer side.

With this configuration, the drug 603 applied to the balloon 602 doesnot flow out when the drug-coated balloon 601 is taken out from a holdertube or accesses a target site in a blood vessel. Accordingly, the drug603 can be effectively applied or released at the target site.

Although examples of application of the main body portion 20 have beendescribed above, the disclosure is not limited to this case. Thedisclosure can be widely applied to the medical instrument 10 forcontrolling liquid circulation through the peripheral wall portion 21 byradially laminating the first layer 30 on which the hydrophilic member33 is disposed and the second layer 40 on which the hydrophobic member43 is disposed.

The detailed description above describes embodiments of a medicalinstrument having a hydrophilic member and a hydrophobic member stacked.The invention is not limited, however, to the precise embodiments andvariations described. Various changes, modifications and equivalents canbe effected by one skilled in the art without departing from the spiritand scope of the invention as defined in the accompanying claims. It isexpressly intended that all such changes, modifications and equivalentswhich fall within the scope of the claims are embraced by the claims.

What is claimed is:
 1. A medical instrument comprising: a main bodyportion having a center hole and a radially outward space partitioned bya tubular peripheral wall portion; the tubular peripheral wall portionincluding at least: a first layer having a hydrophilic member includinga first base portion and a hydrophilic coating formed on the first baseportion; a second layer having a hydrophobic member including a secondbase portion and a hydrophobic coating formed on the second baseportion; and the first layer and the second layer being stacked along aradial direction; and wherein when the hydrophilic coating is swollen,adjacent hydrophilic members come into contact with each other so that afirst liquid in the center hole and a second liquid present in theradially outward space are prevented from circulating through thetubular peripheral wall portion.
 2. The medical instrument according toclaim 1, wherein the first base portion is disposed at a pitchconfigured to allow the swollen hydrophilic coatings of the adjacenthydrophilic members to be in contact with each other.
 3. The medicalinstrument according to claim 1, wherein the second base portion isdisposed at a pitch configured to set a space between the hydrophobiccoatings of the adjacent hydrophobic members to a dimension smaller thana gap through which the first liquid and the second liquid pass.
 4. Themedical instrument according to claim 1, wherein the first base portionand the second base portion have a wire shape or a plate shape.
 5. Themedical instrument according to claim 1, wherein the hydrophilic memberand the hydrophobic member have a coil shape, a ring shape, or a meshshape.
 6. The medical instrument according to claim 1, wherein the mainbody portion constitutes a shaft portion of a catheter.
 7. The medicalinstrument according to claim 1, wherein the main body portionconstitutes a sheath tube of a sheath configured to be percutaneouslyinserted into a body lumen.
 8. The medical instrument according to claim1, wherein the main body portion constitutes a stent configured to beplaced into a body lumen.
 9. The medical instrument according to claim1, wherein the main body portion constitutes a flow diverter stentconfigured to block blood flow between an inner layer side and an outerlayer side and is configured for use in blocking of blood flow betweenan aneurysm and a parent blood vessel.
 10. The medical instrumentaccording to claim 1, wherein the main body portion constitutes anembolic material configured to block blood flow between an inner layerside and an outer layer side and is configured to be placed into ananeurysm and used for blocking an inlet port from a parent blood vesselto the aneurysm.
 11. The medical instrument according to claim 1,wherein the main body portion constitutes a tubular cover memberconfigured to be used in such a manner as to cover a periphery of adrug-coated balloon including a balloon and a drug applied to a surfaceof the balloon, and the cover member is configured to allow the drug onan inner layer side of the cover member to be released to an outer layerside of the cover member when the balloon is operated in a state wherethe balloon is positioned at a target site.
 12. The medical instrumentaccording to claim 1, further comprising: two or more of the first layerand one or more of the second layer; or two or more of the second layerand one or more of the first layer.
 13. A medical instrument comprising:an elongated tubular peripheral wall portion having a central lumen, thetubular peripheral wall portion including at least: a first braidedlayer having a hydrophilic member including a first base portion and ahydrophilic coating formed on the first base portion; and a secondbraided layer having a hydrophobic member including a second baseportion and a hydrophobic coating formed on the second base portion, andwherein the first braided layer and the second braided layer are stackedalong a radial direction; and wherein when the hydrophilic coating isswollen, adjacent hydrophilic members come into contact with each otherso that a first liquid in the central lumen and a second liquid presentin a radially outward space are prevented from circulating through thetubular peripheral wall portion.
 14. The medical instrument according toclaim 13, wherein the first base portion is disposed at a pitchconfigured to allow the swollen hydrophilic coatings of the adjacenthydrophilic members to be in contact with each other; and wherein thesecond base portion is disposed at a pitch configured to set a spacebetween the hydrophobic coatings of the adjacent hydrophobic members toa dimension smaller than a gap through which the first liquid and thesecond liquid pass.
 15. The medical instrument according to claim 13,wherein the first base portion and the second base portion have a wireshape or a plate shape.
 16. The medical instrument according to claim13, wherein the elongated tubular peripheral wall is a shaft portion ofa catheter, a sheath tube of a sheath, a stent, or a flow diverterstent.
 17. The medical instrument according to claim 13, wherein thefirst braided layer is disposed on an outer surface of the secondbraided layer.
 18. The medical instrument according to claim 13, whereinthe second braided layer is disposed on an outer surface of the firstbraided layer.
 19. A medical instrument comprising: a main body portionhaving a lumen and a radially outward space partitioned by a tubularperipheral wall portion; the tubular peripheral wall portion includingat least: a first layer having a hydrophilic member including a firstbase portion and a hydrophilic coating formed on the first base portion;a second layer having a hydrophobic member including a second baseportion and a hydrophobic coating formed on the second base portion; andthe first layer and the second layer being stacked along a radialdirection, and wherein one of the first layer and the second layer iscoiled shape, and another of the first layer and the second layer ismesh shaped; and wherein when the hydrophilic coating is swollen,adjacent hydrophilic members come into contact with each other so that afirst liquid in the lumen and a second liquid present in the radiallyoutward space are prevented from circulating through the tubularperipheral wall portion.